Biobutanol is mainly used in producing plasticizers, such as dibutyl phthalate and aliphatic dicarboxylic acid butyl esters, and is therefore widely used in the production of a variety of plastic and rubber products. Butanol can also be used to produce butyraldehyde, butyric acid, butylamine and butyl acetate, which can be used as the solvents of the resins, paints and adhesives, and also can be used as extractants of greases, drugs, and perfumes, and as additives for alkyd resin coatings. Meanwhile, butanol is also a new biofuel of great potential.
Biobutanol is produced through the method of microbial fermentation, in the method, renewable biomasses, such as starchiness, pulp waste, molasses and wild plants are used as the raw material, and Clostridium acetobutylicum or Clostridium beijerinckii is inoculated thereinto, and then acetone, butanol and ethanol and other products are produced through complicated biochemical changes. Therefore, the above fermentation process for producing biobutanol is also called ABE (acetone-butanol-ethanol) fermentation. Due to toxic effects of butanol on the bacteria, severe product inhibition occurs during the entire fermentation process, and when the concentration of butanol reaches a certain value, the microorganism stops growing, therefore, the concentration of butanol in the fermentation broth is very low, and the cost of recovering butanol by the conventional distillation method is extremely high.
In order to solve this key problem, it is necessary to adopt an effective method to remove the products of ABE from the fermentation broth, reduce the inhibition effect of the products, thereby improving the yield of fermentation and reducing the industrial cost.
Currently, major technologies for separating the fermentation products of ABE include gas stripping (GS), liquid-liquid extraction, pervaporation (PV) and adsorption. Meagher et al. (U.S. Pat. No. 5,755,967) adopt the method of pervaporation to separate acetone and butanol by developing a zeolite membrane filled with silicone rubber, and the zeolite membrane has excellent selective adsorption on acetone and butanol compared with adsorption on the ethanol, acetic acid and butyric acid. Qureshi, N. et al. (Qureshi, N., et al., 2005, Bioprocess and Biosystems Engineering, 27(4): 215-222) recover biobutanol by the method of adsorption-desorption, in terms of energy consumption, the method of adsorption-desorption is the best recovery process, which mainly studies the adsorption performances of some adsorption media, including activated carbon, bone char, siliceous rock, polymer resin XAD-4 and XAD-7, and polyvinyl pyridine resin. However, the total recovery rate of butanol is low due to the following two reasons: on the one hand, the adsorption capacity of the adsorption media is low, such as less than 100 mg butanol/g adsorbent; on the other hand, butanol cannot be desorbed from the adsorbent effectively. DIJK et al. (WO 2008/095896 A1) separate biobutanol by using a hypercrosslinked microporous resin, but the resin adsorbs a certain amount of acetone and ethanol, which increases the cost for later separation processes. Arjan Oudshoorn et al. (Biochemical Engineering Journal 2009, 48:99-103) adopt the zeolite to adsorb and separate biobutanol, and investigate adsorption performances of three zeolites including CBV28014, CBV811, CBV901 on biobutanol, but the problems of this method are that the adsorption capacity of the zeolite on the biobutanol is not high, and acetone and ethanol are also adsorbed while butanol is adsorbed, resulting in the increase of cost for later separation. David R. Nielsen et al. (Biotechnology and Bioengineering 2009, 102(3): 811-821) recover biobutanol in situ by utilizing a polymer resin, and investigates the adsorption performance of the polymer resin on biobutanol, but there are problems on this method, for example the resin contacts with the fermentation broth directly, causing contamination to the resin, some resins have poor biocompatibility, and can adsorb the substrate of glucose and intermediates of the fermentation reaction, some resins have relatively low adsorption capacity, and the resins adsorb large amounts of acetone and ethanol although they have higher adsorption capacity on butanol.